An optical measuring system utilizing light from a laser beam is disclosed in the co-pending application, Ser. No. 566,413, now U.S. Pat. No. 4,043,673 for "Reticle Calibrated Diameter Gauge", by David E. Harris, et al., and assigned to the same assignee. In that co-pending system the occultation of the measuring beam by the workpiece being measured generates signals that are converted to a series of timing pulses operative to control the counting of the calibration pulses. The number of pulses counted, directly related to the dimension of the workpiece being measured is converted to digital signals and so displayed.
It has been found in practice that the measured signal, representative of the workpiece dimension, is affected by the scan velocity, part size, part composition, foreign matter and other forms of noise. Accordingly, the prior art systems, particularly when utilized in certain industrial environments produce measurements that are subjected to error.
Also, there are innumberable pulse forming and pulse shaping circuits known to the prior art; certain of these are intended to generate a series of pulses from a high noise system. A typical example of the prior art pulse forming circuits may be in ignition firing systems. The most reliable of these ignition pulse forming circuits are the one-short multivibrator or blocking oscillator type. But again, the application of the circuits of the prior art is quite distinctive from that of calibration circuits wherein accuracy is most critical.